A dispersion compensation method has been used as a characteristic compensation method in an optical transmission system. For example, there is a method in which the controller calculates the compensation amount of each transmission section based on the actual dispersion amount measured by optical transmission apparatuses and the designed dispersion amount of each transmission section and each optical transmission apparatus compensates the dispersion amount based on the compensation amount reported from the controller. In addition, there is a method in which an optical signal is branched, the branched optical signals are dispersion-compensated, the direction in which the dispersion amount is increased or reduced is decided based on the direction in which the communication quality of one of the compensated optical signals is changed, and the compensation amount of the other optical signal is controlled based on the decision result.
Japanese Laid-open Patent Publication Nos. 2005-318474 and 2011-114402 are examples of related art.